Various attempts have been made to prepare sealant compositions for asphalt and other materials. It has been found that unsealed asphalt becomes porous through use and allows water to seep through the asphaltic particles, causing ground swells which result in cracking of the asphalt surface.
It has been attempted in the past to combine asphaltic materials with copolymers in order to produce sealing compounds. For example, U.S. Pat.No. 3,629,164 teaches the combination of propane-precipitated asphalt with an ethylene-lower alkyl acrylate copolymer. This patent teaches that the mixing occurs at elevated temperatures using the specific propane-precipitated asphalt.
A second attempt to produce such a composition was U.S. Pat. No. 3,951,895. In this latter patent, an asphaltic emulsion was mixed with an emulsion of a copolymer of methyl methacrylate and ethyl acrylate. Although this latter composition proved to be superior to various sealant compositions known at the time, it was found that the methyl methacrylate-ethyl acrylate copolymer was not entirely compatible with commercially available asphaltic emulsions, which resulted in separation and gelling of the composition. It was also found that the methyl methacrylate-ethyl acrylate copolymer did not possess sufficient mechanical stability, which resulted in breakdown during vigorous mixing operations.